Worked on the DragonOS repository to enhance filesystem correctness by implementing Linux-compliant fchown behavior for O_PATH file descriptors. Addressed a kernel-level bug where fchown previously allowed unintended metadata modifications, ensuring that attempts to change ownership on O_PATH file descriptors now return EBADF, consistent with Linux semantics. Expanded automated test coverage using C++ and GTest, introducing regression tests that validate both raw SYS_fchown behavior and standard file descriptor handling. Consolidated O_PATH validation logic to reduce redundant fd_table lookups, improving performance and reliability. Registered new tests in continuous integration workflows, supporting ongoing validation and maintaining cross-component consistency within the system.